CN107764369A - Ultrasonic Liquid Level Measurement - Google Patents
Ultrasonic Liquid Level Measurement Download PDFInfo
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- CN107764369A CN107764369A CN201610705713.7A CN201610705713A CN107764369A CN 107764369 A CN107764369 A CN 107764369A CN 201610705713 A CN201610705713 A CN 201610705713A CN 107764369 A CN107764369 A CN 107764369A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/296—Acoustic waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/296—Acoustic waves
- G01F23/2965—Measuring attenuation of transmitted waves
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- Acoustics & Sound (AREA)
- Electromagnetism (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Abstract
The invention provides a kind of Ultrasonic Liquid Level Measurement, comprise the following steps:Control device controls ultrasonic sensor to send the ultrasonic listening signal of fixed frequency to liquid level, and ultrasonic listening signal rebounds back ultrasonic wave return path signal after liquid level is contacted to ultrasonic sensor;Control device gathers the ultrasonic wave return path signal of reception in real time, simultaneously after control device often gathers a ultrasonic wave return path signal data, the input voltage of real-time dynamic regulation variable gain amplifier to carry out ultrasonic wave return path signal range attenuation dynamic compensation, obtains ultrasonic wave thermal compensation signal;Control device carries out windowing process to ultrasonic wave thermal compensation signal, and target frequency signal is quickly extracted from ultrasonic wave thermal compensation signal with characteristic window.Control device chooses information corresponding to target frequency maximum energy value in ultrasonic wave thermal compensation signal, and outside Energy maximum value position feature scope, chooses information corresponding to second largest energy value.The present invention can provide accurate liquid level result.
Description
Technical field
The present invention relates to e measurement technology and sensing data treatment technology, and specifically, the present invention relates to a kind of ultrasonic wave
Level measuring method.
Background technology
With the development of science and technology, people lead to the municipal administration such as rainwater, sewage, reclaimed water, river course, lake, road with water conservancy
The level monitoring demand in domain is increasing.In recent years, in annual rainy season waterlogging event can all occur for the multiple cities in China, present
The characteristics of occurrence scope is wide, depth of accumulated water is big, the ponding time is long.The generation of waterlogging event, not only go out to the people in the rainy day
Row brings inconvenience, and result in personal and public property massive losses, or even has threatened the life of the people to pacify
Entirely, the extensive concern of all sectors of society is caused.
At present in terms of supersonic liquid level monitoring, feature, stability and the hardware set of miscellaneous equipment become second nature can not be fine
Meet the needs of being monitored for a long time in adverse circumstances.And selling at exorbitant prices, function deficiency, plant section delivery cycle length etc.
Problem, level monitoring and other effects is had a strong impact on.Main performance is as follows:
(1) existing ultrasonic level gage does not do range attenuation dynamic Compensation Design to the ultrasonic energy of passback, can be with
Meet the simple ranging demand of environment, but the complicated application scenario of test environment can not be met, the inaccuracy of ranging can be caused
And saltus step.
(2) existing ultrasonic level gage carries out extraction work using complicated demodulation method to the signal in echo, causes
The complexity of waste and the calculating of hardware resource, so as to compare waste in hardware cost, time construction cycle is grown, in design work
It is more complicated.
(3) existing ultrasonic level gage carries out extracting single Energy maximum value computing, Ke Yiman to the signal in echo
Barrier between sufficient ultrasonic sensor and target object is fewer, and more severe to the installation requirement of ultrasonic level gage
Carve.So that the use occasion of ultrasonic level gage requires stricter, it is less desirable in the ranging effect of ultrasonic level gage.
It would therefore be highly desirable to there is a kind of level gauging requirement that can adapt to complex environment and simple and effective level gauging side
Method.
The content of the invention
In order to solve the above technical problems, the invention provides a kind of level gauging requirement and letter that can adapt to complex environment
Single effective level measuring method.
The technical solution adopted by the present invention is:
Embodiments of the invention provide a kind of Ultrasonic Liquid Level Measurement, including:Control device controls supersonic sensing
Device sends the ultrasonic listening signal of fixed frequency to tested liquid level, the ultrasonic listening signal after the liquid level is contacted,
Rebounded back ultrasonic wave return path signal to the ultrasonic sensor;The control device gathers the ultrasonic wave passback letter of reception in real time
Number, while after control device often gathers a ultrasonic wave return path signal, real-time dynamic regulation variable gain amplifier it is defeated
Enter voltage and to carry out the ultrasonic wave return path signal range attenuation dynamic compensation, obtain ultrasonic wave thermal compensation signal;The control
Device carries out windowing process to the ultrasonic wave thermal compensation signal, is quickly extracted with characteristic window from the ultrasonic wave thermal compensation signal
Target frequency signal;The control device chooses letter corresponding to target frequency maximum energy value in the ultrasonic wave thermal compensation signal
Breath, and outside Energy maximum value position feature scope, choose information corresponding to second largest energy value;The control device base
Information corresponding to the second largest energy value of information corresponding to maximum energy value in selected target frequency and selection target frequency,
The information corresponding to liquid level described in effective ultrasonic reflections is obtained, calculates liquid of the ultrasonic sensor apart from the liquid level
Position height.
Preferably, the control device drives the first digital analog converter to send the ultrasonic listening of fixed frequency and believed
Number, the detectable signal of transmission is sent after amplifying through power amplifier by the ultrasonic sensor;The control device control
Analog-digital converter processed is described to be gathered more than 2 times of sample frequency of the highest frequency in the ultrasonic wave return path signal
Ultrasonic wave return path signal;The input voltage of the variable gain amplifier to the ultrasonic wave return path signal with carrying out range attenuation
The gain energy value of dynamic compensation is directly proportional.
Preferably, after the control device often gathers a ultrasonic wave return path signal, control device passes through control second
The voltage that digital analog converter output continuously changes carrys out the input voltage of variable gain amplifier described in dynamic regulation, and then
Gain energy value described in dynamic regulation, to carry out range attenuation compensation to next collection point of the ultrasonic wave return path signal.
Preferably, the ultrasonic listening signal that control device control ultrasonic sensor is sent includes fixed NperiodIt is individual
The sine wave signal in cycle, the control device are analyzed the ultrasonic wave thermal compensation signal, extract the ultrasonic wave compensation
N in signalperiodThe positional information of individual cycle Sine wave signal, and ultrasonic sensor is calculated to the distance of tested liquid level.
Preferably, control device carries out windowing process to the ultrasonic wave thermal compensation signal, using characteristic window size
The ultrasonic wave thermal compensation signal divided data section is analyzed, wherein characteristic window size is obtained by equation below:
SIZEwindow=Nperiod*fsample/fsend, wherein, SIZEwindowFor signal transacting window size, NperiodFor supersonic sensing
Device sends waveform periodicity, fsampleSignal frequency, f are gathered for control devicesendSignal frequency is sent for ultrasonic probe.
Preferably, control device does signal extraction characteristic point to be compensated from the ultrasonic wave using 1 and -1 two characteristic value
The positional information of rapid extraction target frequency signal in signal.
Preferably, information corresponding to information corresponding to the maximum energy value and the second largest ability maximum includes:
The maximum points P of energy in ultrasonic wave return path signalfmax, the ENERGY E of the maximum points of energy in ultrasonic wave return path signalfmax, surpass
In sound wave return path signal outside Energy maximum value position feature value scope time big points P of energysmax, ultrasonic wave return path signal
The ENERGY E of the big points of middle energy timesmax。
Preferably, in addition to:Control device returns to the information and ultrasonic wave of energy maximum point in ultrasonic wave return path signal
The a little bigger information of energy time carries out filtration treatment in signal, and the parameter being related in filter process includes:Ultrasonic wave passback letter
Energy one-level threshold values E in numbervalid1, energy two level threshold values E in ultrasonic wave return path signalvalid2, the last effective ultrasonic wave
The maximum points P of energy in return path signallastmax, the energy of the maximum points of energy in the last effective ultrasonic return path signal
Measure Elastmax, maximum point flag bit Flag in ultrasonic reflections object return path signalEfmax, energy time is big in ultrasonic wave return path signal
Point flag bit FlagEsmax, the maximum points of energy allow to change threshold values with last measurement virtual value in ultrasonic wave return path signal
Pchange, there is virtual value flag bit Flag in middle energy in ultrasonic wave return path signalsuccess。
Preferably, information of the control device based on following filtration treatment principle to energy maximum point in ultrasonic wave return path signal
Filtration treatment is carried out with a little bigger information of energy in ultrasonic wave return path signal time:
1)
Work as Efmax≥Evalid1When, if Efmax≥Evalid2, then FlagEfmax=2
Work as Efmax≥Evalid1When, if | Pfmax-Plastmax|≤Pchange, then FlagEfmax=1
Work as Efmax≥Evalid1When, if | Pfmax-Plastmax|>Pchange, then FlagEfmax=0
Work as Efmax<Evalid1When, FlagEfmax=0
2)
Work as Esmax≥Evalid1When, if Esmax≥Evalid2, FlagEsmax=2
Work as Esmax≥Evalid1When, if | Psmax-Plastmax|≤Pchange, FlagEsmax=1
Work as Esmax≥Evalid1When, if | Psmax-Plastmax|>Pchange, FlagEsmax=0
Work as Esmax<Evalid1When, FlagEsmax=0
3)
Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax=0, then Flagsuccess=0;
Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax≠ 0 and
|Pfmax-Plastmax|≤|Psmax-Plastmax|, then Flagsuccess=1, Plastmax=Pfmax,Elastmax=Efmax;
Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax≠ 0 and
|Pfmax-Plastmax|>|Psmax-Plastmax|, then Flagsuccess=1, Plastmax=Psmax, Elastmax=Esmax;
Work as FlagEfmax≠FlagEsmaxWhen, Flagsuccess=1, Plastmax=Pfmax, Elastmax=Efmax。
Preferably, control device obtains P according to the filtration treatment principlelastmax, ElastmaxAnd FlagsuccessIt is specific
Numerical value, and calculate distance of the ultrasonic sensor apart from liquid level according to following formula:
H2=Plastmax*Vspeed/2/fsampleWherein:H2Distance for ultrasonic sensor apart from liquid level;PlastmaxFor most
The maximum points of energy in nearly once effective ultrasonic wave return path signal;VspeedFor the aerial spread speed of sound;fsample
For the sample rate of analog-digital converter.
The Ultrasonic Liquid Level Measurement of the present invention does range attenuation dynamic Compensation Design to the ultrasonic energy of passback, can
To meet the complicated application scenario of test environment, precise and stable ranging can be obtained;Employ simple 1 and -1 two simultaneously
Characteristic value does the positional information that signal extraction characteristic point carrys out the rapid extraction target frequency signal from the ultrasonic wave thermal compensation signal,
So that calculating process is simplified, the resource of processor has been saved.In addition, it is extracted maximum energy value and second largest Energy maximum value
Two values, while information corresponding to information corresponding to maximum energy value and second largest Energy maximum value is carried out using principle is filtered
Filtering, so as to improving the interference rejection ability of ranging.
Brief description of the drawings
Fig. 1 shows the flow chart of the Ultrasonic Liquid Level Measurement of one embodiment of the invention.
Fig. 2 shows the hardware module schematic diagram of the range unit of one embodiment of the invention.
Fig. 3 shows the onsite application installation diagram of the distance-measuring equipment of one embodiment of the invention.
Fig. 4 shows that ultrasonic echo signal does not enter the original signal waveform of row distance dynamic compensation.
Fig. 5 shows that ultrasonic echo signal enters the original signal waveform of row distance dynamic compensation.
Fig. 6 shows the waveform that ultrasonic echo signal is not entered after row distance dynamic compensation extraction energy value.
Fig. 7 shows that ultrasonic echo signal carries out the waveform after dynamic power compensation extraction energy value.
Fig. 8 shows that ultrasonic echo signal carries out the original signal waveform of dynamic power compensation.
Fig. 9 shows the waveform after rapid extraction energy value from ultrasonic echo signal.
Embodiment
The embodiment of the present invention is described below in conjunction with accompanying drawing.
Fig. 1 shows the flow chart of the ultrasonic ranging method of one embodiment of the invention, and Fig. 2 shows the present invention one
The hardware module schematic diagram of the range unit of embodiment, Fig. 3 show that the scene of the distance-measuring equipment of one embodiment of the invention makes
Use installation diagram.
First, it is described referring to figs. 2 and 3 the range unit to being applied in the present invention.As shown in figure 3, as one
Schematical embodiment, the control device with processing function and ultrasonic sensor can be arranged on to the top of well, with to well
Liquid level be monitored, certainly, the invention is not limited in the liquid level for liquid level of adjusting the distance measures, other can also be adjusted the distance
The height of target object measures.In figure 3, the implication respectively marked is as follows:
1)H1:Sonac bottom is away from well head distance=sensor stand away from well head distance+sensor stand away from ultrasound
Sensor base distance.
2)H2:Sonac bottom is away from water surface distance.
3)H3:Depth of water height.
4)H4:Well depth height.
5)H5:Early warning liquid level.
6)H6:Alarm liquid level.
In one embodiment of this invention, H1=0.78 meter, H4=8.12 meters, H5=2.00 meters, H6=5.00 meters, liquid level
Height H3=1.51 meters.The calculating target of the present invention is H2, then will be described.
Fig. 2 shows the range unit hardware module schematic diagram of one embodiment of the invention, and application hardware module is mainly wrapped
Include:Processor (MCU), PLD (CPLD), digital analog converter (DA1), power amplifier (PA), digital mould
Plan converter (DA2), analog-digital converter (AD), variable gain amplifier (VGA), transceiver ultrasonic sensor, its
Middle processor and PLD may make up the control device of range unit, and remaining module is controlled, and each module can
Communication connection is carried out according to relation illustrated in fig. 2, the present invention can also be used two ultrasonic sensors super to send and receive
Acoustic signals, and not only use transceiver ultrasonic sensor.Specifically, in the present invention, processor mainly plays control
Effect, between processor and PLD by Serial Peripheral Interface (SPI) (SPI) realize control command issue and data
Transmission.The hair ripple order of programmable logic device (CPLD) reception processing device, control digital analog converter DA1 send signal,
Ultrasonic sensor is driven to send ultrasonic wave, the ultrasound of transmission to target object (being liquid level in the present invention) by power amplifier
Ripple rebounds back ultrasonic sensor after liquid level is encountered;The compensation order that programmable logic device (CPLD) reception processing device is sent,
Control variable gain amplifier VGA to carry out range attenuation dynamic to the ultrasound information of passback to compensate, to eliminate liquid as far as possible
Face surrounding enviroment are to interference caused by the ultrasonic signal of passback;Also, the letter that PLD reception processing device is sent
Number acquisition, control analog-digital converter collection ultrasonic wave return path signal, ultrasonic wave of the PLD to collection
Return path signal is analyzed and processed, and obtains information corresponding to information corresponding to maximum energy value and second largest energy value, may be programmed
Logical device is by information back is to processor corresponding to information corresponding to the maximum energy value and second largest energy value, and processor is most
The distance values of ultrasonic sensor and target object are obtained afterwards.
Next, with reference to Fig. 1, Fig. 4 to Fig. 9 (referring to figs. 2 and 3) and preferred embodiment to supersonic liquid level of the invention
Measuring method is introduced.
As shown in figure 1, the Ultrasonic Liquid Level Measurement of the present invention comprises the following steps:
Step 101:Measuring system initializes, and electricity on the modules in system, starts ranging process.Specifically, handle
Device is communicated by Serial Peripheral Interface (SPI) (SPI) with PLD (CPLD), PLD (CPLD) initialization
Digital analog converter (DA1), the output voltage of digital analog converter (DA1) is transferred to center, power amplifier
(PA) center is transferred in output, and processor is communicated by Serial Peripheral Interface (SPI) (SPI) with PLD, may be programmed
Logical device (CPLD) initialization digital analog converter (DA2), by the output voltage set to zero of digital analog converter (DA2)
Point position, digital analog converter (DA2) regulation variable gain amplifier (VGA) enter to ultrasonic sensor passback return path signal
The processing of row zero-compensation.Meanwhile processor is communicated by Serial Peripheral Interface (SPI) (SPI) with PLD, FPGA
Device (CPLD) initialization analog-digital converter (AD), is operated in non-low-power consumption mode by analog-digital converter (AD), makes
Analog-digital converter (AD) is obtained to start working.Above-mentioned all modules are ready to, and wait processor to be sent out to PLD
Send ranging order.
Step 102:Prestored 16 sine wave characteristics points in PLD, and these sine wave characteristics points are in order
Curve is drawn as, the sine wave curve of a cycle can be depicted as.Processor is sent by SPI interface to PLD
Ranging order, PLD driving digital analog converter (DA1) send the sine that 16 period frequencies are 40Khz
Ripple, digital analog converter (DA1), which exports the waveform, gives power amplifier (PA), and power amplifier PA is by the sine wave of reception
The power of signal is amplified, and driving ultrasonic sensor sends ultrasonic listening signal to testee (liquid level).
Step 103:After ultrasonic sensor sends ultrasonic listening signal to tested liquid level, processor is connect by SPI
Mouth sends signal compensation order, the input of programmable logic device regulation digital analog converter (DA2) to PLD
Digital quantity, driving VGA dynamics compensate the range attenuation of ultrasonic energy, and digital analog converter DA2 of the invention is inputted first
Beginning digital quantity is 15000, and the latter digital quantity is incremented by one by one using step sizes as 5, the numeral of digital analog converter DA2 inputs
It is 8000 to measure total number, but is not limited thereto, for example, it is also possible to using 16 points as a cycle, preceding 9 points output is incremented by 5,
7 point outputs are incremented by 6 afterwards;Meanwhile PLD gathers the ultrasonic wave passback of compensation by analog-digital converter AD
Signal, sample frequency should meet Nyquist's theorem, because in the transfer process for carrying out analog/digital signal, when sampling frequency
Rate fsmaxMore than highest frequency f in return path signalmax2 times when (fsmax>2fmax), the data signal after sampling intactly retains
Information in primary signal.Analog-digital converter AD in the present invention in the transfer process for carrying out analog and digital signal,
One sample frequency for implementing to exemplify is 4 times of highest return path signal frequency, i.e. sample frequency is 160Khz.
In the present invention, ultrasonic sensor sends fixed NperiodIndividual cycle ultrasonic signal, these signals touch mesh
After marking object, can rebound back ultrasonic wave, and the ultrasonic signal to rebound back returns to ultrasonic sensor.Ultrasonic wave returns in atmosphere
During biography, with the increase of transmission range, the total energy value of ultrasonic wave can decay, and ultrasonic sensor receives
Energy value is inversely proportional with ultrasonic transmission distance, is expressed as by formula:Esound=Et–K1*Sdistance.Wherein:EsoundIt is super
The ultrasonic wave that sonic sensor is sent, is contacted, rebound the ultrasonic energy value returned with objects in front;K1It is ultrasonic wave in air
Among propagate, with the increase of distance, the attenuation slope of ultrasonic energy value;SdistanceFor ultrasonic sensor and objects in front
Distance, be ultrasonic wave in atmosphere pass through total path half;EtLaunch ultrasonic wave gross energy for ultrasonic sensor.
Compensation to the ultrasonic signal of passback is specially:The input voltage of CPLD regulation variable gain amplifiers (VGA),
The energy value of dynamic compensation ultrasonic distance decay in real time, the dynamic compensation energy value and variable gain of variable gain amplifier
The input voltage of amplifier is directly proportional, is expressed as by formula:Evga=K2*VDA2.Wherein:EvgaIncrease for variable gain amplifier
Benefit value;K2For variable-gain amplifier gain slope;VDA2For digital analog converter DA2 output voltage values.
Wherein, variable gain amplifier VGA input voltage, the input digital value with digital analog converter DA2 is into just
Than being expressed as by formula:VDA2=VDA2ref*DDAin/Dnum, wherein, VDA2refFor digital analog converter DA2 reference voltages;
DDainFor digital analog converter DA2 output numeral numerical quantity;VDA2For variable gain amplifier VGA input voltage;Dnum
Digital quantity total value is exported for digital analog converter DA2.
The energy that can be decayed by the size for the input voltage for adjusting variable gain device (VGA) come dynamic uncompensation distance
Value.Compensated distance factor Ⅴm=K1/K2, wherein, K1For the range attenuation slope of ultrasonic energy value, K2To amplify for variable gain
Device gain slope, VmFor the VGA compensated distance factors.
Can be by adjusting digital analog converter DA2 input digital quantity size, to adjust variable gain amplifier VGA's
Input voltage.Digital compensation factor Dm=Vm*Dnum/VDA2ref, wherein:VmFor the compensated distance factor, DmFor digital analog converter
The DA2 digital compensation factor.
In the present invention, ultrasonic distance Regime during recession is compensated by controlling digital analog converter DA2 voltage
Method is Dvga=Dt/f, wherein:Dvga is the digital increments that DA2 each puts output, and Dt is the numeral increasing of DA2 outputs per second
Amount, f is DA2 output frequencies, and in the present invention, the compensation frequency of VGA range attenuations dynamic compensation is 40Khz.
That is, programmable logic device (CPLD) is adjusted by adjusting the digital quantity size inputted to digital analog converter DA2
DA2 output voltage is saved, and then adjusts variable gain amplifier VGA input voltage, finally to the energy of ultrasonic wave return path signal
Value enters Mobile state compensation.
Show that ultrasonic echo signal does not enter the primary signal figure of row distance dynamic compensation in Fig. 4.Fig. 5 is shown
Ultrasonic echo signal carries out the primary signal figure of dynamic power compensation.Ultrasonic wave original echoed signals shown in Fig. 4 and Fig. 5 are all
It is that nearby waveforms amplitude is bigger in 800 points (interference signals) and 5450 points (liquid level signals), illustrates there is reverberation at two at this
Body echo-signal.After Fig. 4 and Fig. 5 difference is that ultrasonic wave original echoed signals carry out dynamic power compensation, ultrasonic wave is original
Echo-signal can be made up with energy attenuation caused by distance.Fig. 4 and signal illustrated in fig. 5 will be described at step 104
Rapid extraction energy value result.
Step 104:PLD handles the ultrasonic wave compensation that analog-digital converter AD collections are returned in real time
Return path signal, carries out windowing process to thermal compensation signal, the calculation formula of the characteristic window size used for:SIZEwindow=
Nperiod*fsample/fsend, wherein:SIZEwindowFor signal transacting window size, NperiodThe ripple sent for ultrasonic sensor
Shape periodicity, fsampleThe frequency of signal, f are gathered for processorsendThe signal frequency sent for ultrasonic probe, in the present invention
In, due to NperiodFor 16, fsampleFor 160Khz, fsendFor 40Khz, the size for so obtaining signal transacting window is 64.Together
When PLD rapid extraction 40Khz target frequency signal energy value, that is, each point by thermal compensation signal
Multiplying is carried out with corresponding sine wave characteristics point, then the multiplication result of this signaling point and the multiplication knot of signaling point below
Fruit carries out summation operation, and the number of summation operation is window size, finally obtains the energy value of this signaling point.The present invention uses
1 and -1 two characteristic value do the sine wave characteristics point of rectified signal, each cycle takes 4 characteristic points, that is, 1,1, -1, -1;
Each data, which are multiplied by 1 calculation procedure, in signal can be reduced to the number of winning the confidence itself, and each data are multiplied by -1 calculating in signal
Step can be reduced to the opposite number for the number of winning the confidence, and then, the operation result of 64 signaling points in characteristic window is summed
Computing, the energy value of the thermal compensation signal point is obtained, and so on, it can obtain the energy value of each signaling point, each characteristic window
Positional information corresponding to interior energy value is first signaling point that the window starts.The present invention uses 1,1, -1, -1 conduct
Characteristic value, both simplifies calculating process, has saved the resource of processor again.
Fig. 6 shows the waveform that ultrasonic echo signal is not entered after row distance dynamic compensation extraction energy value.Fig. 7 is shown
Ultrasonic echo signal carries out the waveform after dynamic power compensation extraction energy value.Ultrasonic echo letter shown in Fig. 6 and Fig. 7
Waveform after number extraction energy value is all peak value occur 800 (interference signals) point and 5450 (liquid level signals) point are neighbouring, explanation
Ultrasonic signal has reflection at two at this.Fig. 6 and Fig. 7 difference is, the shown chaff interference meetings near from ultrasonic sensor of Fig. 6
Erroneous effects are caused to ranging, the near chaff interference of ultrasonic sensor shown in Fig. 7 can make minor impact to ranging, Fig. 6 and Fig. 7 pairs
Than the antijamming capability that ranging can be improved after explanation ultrasonic echo signal progress dynamic power compensation.
Fig. 8 shows that ultrasonic echo signal carries out the primary signal figure of dynamic power compensation.Ultrasonic wave original echo
Nearby waveforms amplitude is bigger in 3750 points (chute interference signals) and 5450 points (liquid level signals) for signal, illustrates have at two at this
Reflect object echo-signal.Fig. 9 shows the waveform after rapid extraction energy value in Fig. 8 ultrasonic echo signals, in step 105
Describe Fig. 9 waveforms and take bimodal, the result after filter algorithm.
Step 105:PLD finds out maximum energy value and second largest energy in the energy value of thermal compensation signal
Maximum, and their active position information is extracted, including:Energy maximum in ultrasonic reflections object returns (return path signal)
Count Pfmax, the ENERGY E of the maximum points of energy in ultrasonic reflections object returnsfmax, distance in ultrasonic reflections object returns
The big points P of the outer energy time of Energy maximum value position feature value scopesmax, the big point of energy time in ultrasonic reflections object returns
Several ENERGY Essmax.Show to extract in the waveform of ultrasonic echo signal energy value from Fig. 9 bimodal, P can be obtainedfmax=3777,
Efmax=46990000, Psmax=5493, Esmax=39150000.
PLD is by the P of extractionfmax, Efmax, Psmax, EsmaxNumerical value is transmitted to processor by SPI interface, connects
, processor is to Pfmax, Efmax, Psmax, EsmaxFiltration treatment is carried out, the parameter being related in filter process includes:Ultrasonic wave
Reflect object backward energy one-level threshold values Evalid1, ultrasonic reflections object returns energy two level threshold values Evalid2, the last time has
The maximum points P of energy in the ultrasonic reflections object returns of effectlastmax, the last effective ultrasonic reflections object returns
The ENERGY E of the maximum points of middle energylastmax;Energy maximum point flag bit Flag in ultrasonic reflections object returnsEfmax, ultrasound
The a little bigger flag bit Flag of energy time in wave reflection object returnsEsmax;In ultrasonic reflections object returns the maximum points of energy with
Last time measurement virtual value allows to change threshold values Pchange;In ultrasonic reflections object returns there is virtual value flag bit in energy
Flagsuccess.Wherein, Evalid1、Evalid2、Elastmax、PchangeValue storage within a processor, be definite value.Ultrasonic reflections thing
Energy maximum point flag bit Flag in body echoEfmaxWith a little bigger flag bit Flag of energy in ultrasonic reflections object returns timeEsmax
What is reacted is the energy grade of Energy maximum value and energy second largest value, in the present invention, using 0,1 and 2 energy as flag bit
Grade is measured, using that in determination selection Energy maximum value and energy second largest value as virtual value, wherein 0 represents lowermost level, 2 tables
Show the superlative degree.In ultrasonic reflections object returns there is virtual value flag bit Flag in energysuccessReaction is this ranging
Data validity.0 represents that this ranging is invalid, and 1 represents that this ranging is effective.
Step 106:Information and ultrasonic reflections object of the processor to energy maximum point in ultrasonic reflections object returns
The a little bigger information of energy time carries out filtration treatment in echo, and energy maximum point and ultrasonic wave are anti-from ultrasonic reflections object returns
Penetrate energy in object returns time it is a little bigger in find out the information of point in effective ultrasonic reflections object returns, filtration treatment according to
Following principle:
(1)
Work as Efmax≥Evalid1When, if Efmax≥Evalid2, then FlagEfmax=2
Work as Efmax≥Evalid1When, if | Pfmax-Plastmax|≤Pchange, then FlagEfmax=1
Work as Efmax≥Evalid1When, if | Pfmax-Plastmax|>Pchange, then FlagEfmax=0
Work as Efmax<Evalid1When, FlagEfmax=0
(2)
Work as Esmax≥Evalid1When, if Esmax≥Evalid2, FlagEsmax=2
Work as Esmax≥Evalid1When, if | Psmax-Plastmax|≤Pchange, FlagEsmax=1
Work as Esmax≥Evalid1When, if | Psmax-Plastmax|>Pchange, FlagEsmax=0
Work as Esmax<Evalid1When, FlagEsmax=0
(3)
Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax=0, then Flagsuccess=0;
Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax≠ 0 and
|Pfmax-Plastmax|≤|Psmax-Plastmax|, then Flagsuccess=1, Plastmax=Pfmax,Elastmax=Efmax;
Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax≠ 0 and
|Pfmax-Plastmax|>|Psmax-Plastmax|, then Flagsuccess=1, Plastmax=Psmax, Elastmax=Esmax;
Work as FlagEfmax≠FlagEsmaxWhen, Flagsuccess=1, Plastmax=Pfmax, Elastmax=Efmax。
Above-mentioned filtering principle (1) is used to determine energy maximum point flag bit FlagEfmax, that is, determine Energy maximum value etc.
Level, above-mentioned filtering principle (2) are used to determine a little bigger flag bit Flag of energy timeEsmax, that is, determine energy second largest value grade, then
According to the result of filtering principle (1) and (2), to choose effective marker position, and determine by energy maximum number of points and its energy value with
That in energy second largest value points and its energy value is as the last effective ultrasonic reflections object returns points and energy
Value.Flagsuccess=1 represents ranging success, Flagsuccess=0 represents that ranging is unsuccessful, and ranging success can obtain effectively
Liquid level information, and test unsuccessful, effective liquid level information can not be obtained.
In one embodiment of this invention, Evalid1=10000000, Evalid2=30000000, Plastmax=5470,
Elastmax=32230000, Pchange=50.So, with reference to Fig. 8 and waveform illustrated in fig. 9, simple extraction maximum energy value
Positional information calculates, and obtained result is:Flagsuccess=1, Plastmax=3777, Elastmax=46990000;Simple
Extraction maximum energy value positional information calculates, and does not extract two peak values and does filtration treatment, obtains the position of chute interference signal
Confidence ceases, and is wrong liquid level information.The result after bimodal filtered processing is taken to be:Flagsuccess=1, Plastmax=5493,
Elastmax=39150000, it is correct liquid level information.It can be seen from the above results, the positional information of maximum point energy value have chosen
Time a little bigger positional information and after carrying out filtration treatments to them with energy, obtained PlastmaxAnd ElastmaxHave with the last time
The P of effectlastmaxAnd ElastmaxIt is more close, it follows that in ultrasonic reflections object returns energy maximum point information and ultrasonic wave
The secondary a little bigger information of energy in object returns is reflected after above-mentioned filtering principle filtration treatment, it is possible to increase the anti-interference energy of ranging
Power.As shown in figure 9, two two peak values of extraction do filtration treatment, correct liquid level is obtained, the specific algorithm of liquid level is referring to following steps
Rapid 107.
Step 107:Calculate liquid level H2。
Processor obtains the information P of the point in effective ultrasonic reflections object returns according to filtration treatmentlastmax, use
Formula H2=Plastmax*Vspeed/2/fsampleTo calculate liquid level H2.Wherein:PlastmaxFor the last effective ultrasonic reflections
The maximum points of energy, V in object returnsspeedFor the aerial spread speed of sound, fsampleFor analog-digital converter AD
Sample frequency.
In one embodiment of this invention, the P calculated according to step 106lastmax, processor collection signal frequency
fsampleAnd VspeedTo calculate H2, finally give H2=5.83 meters.This level gauging is completed, and each module is powered-down.
Device embodiment described above is only schematical, wherein can be as the unit that separating component illustrates
Or may not be physically separate, it can be as the part that unit is shown or may not be physical location, i.e.,
A place can be located at, or can also be distributed on multiple NEs.It can select according to the actual needs therein
Some or all of module realizes the purpose of this embodiment scheme.Those of ordinary skill in the art are not paying the labor of creativeness
In the case of dynamic, you can to understand and implement.
Through the above description of the embodiments, those skilled in the art can be understood that each embodiment can
Realized by the mode of software plus required general hardware platform, naturally it is also possible to pass through hardware.Based on such understanding, on
The part that technical scheme substantially in other words contributes to prior art is stated to embody in the form of software product, should
Computer software product can store in a computer-readable storage medium, such as ROM/RAM, magnetic disc, CD, including some fingers
Make to cause a computer equipment (can be personal computer, server, or network equipment etc.) to perform each implementation
The method of some parts of example or embodiment.
Finally it should be noted that:The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations;Although
The present invention is described in detail with reference to the foregoing embodiments, it will be understood by those within the art that:It still may be used
To be modified to the technical scheme described in foregoing embodiments, or equivalent substitution is carried out to which part technical characteristic;
And these modification or replace, do not make appropriate technical solution essence depart from various embodiments of the present invention technical scheme spirit and
Scope.
Claims (10)
- A kind of 1. Ultrasonic Liquid Level Measurement, it is characterised in that including:Control device controls ultrasonic sensor to the ultrasonic listening signal of tested liquid level transmission fixed frequency, the ultrasonic wave Detectable signal rebounds back ultrasonic wave return path signal after the liquid level is contacted to the ultrasonic sensor;The control device gathers the ultrasonic wave return path signal of reception in real time, while often gathers a ultrasonic wave in control device and return After passing signal, the input voltage of real-time dynamic regulation variable gain amplifier enters row distance to the ultrasonic wave return path signal Regime during recession compensates, and obtains ultrasonic wave thermal compensation signal;The control device carries out windowing process to the ultrasonic wave thermal compensation signal, is quickly mended with characteristic window from the ultrasonic wave Repay extraction target frequency signal in signal;The control device chooses information corresponding to target frequency maximum energy value in the ultrasonic wave thermal compensation signal, and away from Outside from Energy maximum value position feature scope, information corresponding to second largest energy value is chosen;The second of information corresponding to maximum energy value of the control device based on selected target frequency and selection target frequency Information corresponding to big energy value, obtains the information corresponding to liquid level described in effective ultrasonic reflections, calculates the ultrasonic wave and passes Liquid level of the sensor apart from the liquid level.
- 2. Ultrasonic Liquid Level Measurement according to claim 1, it is characterised in that the number of control device driving first Word analog converter send fixed frequency ultrasonic listening signal, the detectable signal of transmission after amplifying through power amplifier, Sent by the ultrasonic sensor;The control device controls analog-digital converter with 2 times more than the highest frequency in the ultrasonic wave return path signal Sample frequency gathers the ultrasonic wave return path signal;The input voltage of the variable gain amplifier is with carrying out range attenuation dynamic compensation to the ultrasonic wave return path signal Gain energy value is directly proportional.
- 3. Ultrasonic Liquid Level Measurement according to claim 2, it is characterised in that the control device often gathers one After ultrasonic wave return path signal, control device is moved by the voltage for controlling the output of the second digital analog converter continuously to change State adjusts the input voltage of the variable gain amplifier, and then gain energy value described in dynamic regulation, with to the ultrasonic wave Next collection point of return path signal carries out range attenuation compensation.
- 4. Ultrasonic Liquid Level Measurement according to claim 1, it is characterised in that control device controls supersonic sensing The ultrasonic listening signal that device is sent includes fixed NperiodThe sine wave signal in individual cycle, the control device is to described super Sound wave thermal compensation signal is analyzed, and extracts N in the ultrasonic wave thermal compensation signalperiodThe positional information of individual cycle Sine wave signal, And ultrasonic sensor is calculated to the distance of tested liquid level.
- 5. Ultrasonic Liquid Level Measurement according to claim 4, it is characterised in that:Control device is mended to the ultrasonic wave Repay signal and carry out windowing process, the ultrasonic wave thermal compensation signal divided data section is analyzed using characteristic window size, Wherein characteristic window size is obtained by equation below:SIZEwindow=Nperiod*fsample/fsend, wherein, SIZEwindowFor letter Number processing window size, NperiodWaveform periodicity, f are sent for ultrasonic sensorsampleSignal frequency is gathered for control device, fsendSignal frequency is sent for ultrasonic probe.
- 6. Ultrasonic Liquid Level Measurement according to claim 4, it is characterised in that control device is using 1 and -1 two Characteristic value does the positional information that signal extraction characteristic point carrys out the rapid extraction target frequency signal from the ultrasonic wave thermal compensation signal.
- 7. Ultrasonic Liquid Level Measurement according to claim 1, it is characterised in that believe corresponding to the maximum energy value Information corresponding to breath and the second largest ability maximum includes:The maximum points P of energy in ultrasonic wave return path signalfmax, surpass The ENERGY E of the maximum points of energy in sound wave return path signalfmax, apart from Energy maximum value position feature in ultrasonic wave return path signal It is worth the big points P of the outer energy time of scopesmax, the ENERGY E of the big points of energy time in ultrasonic wave return path signalsmax。
- 8. Ultrasonic Liquid Level Measurement according to claim 7, it is characterised in that also include:Control device is to ultrasound The a little bigger information of energy time carries out filtration treatment, mistake in the information of energy maximum point and ultrasonic wave return path signal in ripple return path signal The parameter being related in filter processing procedure includes:Energy one-level threshold values E in ultrasonic wave return path signalvalid1, in ultrasonic wave return path signal Energy two level threshold values Evalid2, the maximum points P of energy in the last effective ultrasonic wave return path signallastmax, it is the last The ENERGY E of the maximum points of energy in effective ultrasonic return path signallastmax, maximum point in ultrasonic reflections object return path signal Flag bit FlagEfmax, a little bigger flag bit Flag of energy time in ultrasonic wave return path signalEsmax, energy is most in ultrasonic wave return path signal Big points allow to change threshold values P with last measurement virtual valuechange, there is virtual value in middle energy in ultrasonic wave return path signal Flag bit Flagsuccess。
- 9. Ultrasonic Liquid Level Measurement according to claim 8, it is characterised in that control device is based at following filtering Reason principle is entered to a little bigger information of energy in the information and ultrasonic wave return path signal of energy maximum point in ultrasonic wave return path signal time Row filtration treatment:1)Work as Efmax≥Evalid1When, if Efmax≥Evalid2, then FlagEfmax=2Work as Efmax≥Evalid1When, if | Pfmax-Plastmax|≤Pchange, then FlagEfmax=1Work as Efmax≥Evalid1When, if | Pfmax-Plastmax|>Pchange, then FlagEfmax=0Work as Efmax<Evalid1When, FlagEfmax=02)Work as Esmax≥Evalid1When, if Esmax≥Evalid2, FlagEsmax=2Work as Esmax≥Evalid1When, if | Psmax-Plastmax|≤Pchange, FlagEsmax=1Work as Esmax≥Evalid1When, if | Psmax-Plastmax|>Pchange, FlagEsmax=0Work as Esmax<Evalid1When, FlagEsmax=03)Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax=0, then Flagsuccess=0;Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax≠ 0 and|Pfmax-Plastmax|≤|Psmax-Plastmax|, then Flagsuccess=1, Plastmax=Pfmax,Elastmax=Efmax;Work as FlagEfmax=FlagEsmaxWhen, if FlagEfmax≠ 0 and|Pfmax-Plastmax|>|Psmax-Plastmax|, then Flagsuccess=1, Plastmax=Psmax, Elastmax=Esmax;Work as FlagEfmax≠FlagEsmaxWhen, Flagsuccess=1, Plastmax=Pfmax, Elastmax=Efmax。
- 10. Ultrasonic Liquid Level Measurement according to claim 9, it is characterised in that control device is according to the filtering Treatment principle obtains Plastmax, ElastmaxAnd FlagsuccessConcrete numerical value, and calculate supersonic sensing according to following formula Distance of the device apart from liquid level:H2=Plastmax*Vspeed/2/fsampleWherein:H2Distance for ultrasonic sensor apart from liquid level;PlastmaxFor nearest one The maximum points of energy in secondary effective ultrasonic wave return path signal;VspeedFor the aerial spread speed of sound;fsampleFor mould Intend the sample rate of digital quantizer.
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